Telephone-exchange system.



vLira roLINKoWsKY, or BRUSSELS, BELG1UM,.-iA-ssrenon fro WESTERN ELECTRIC COMPANY, or NEW YoBK,.N. Y.,- AcoRPoRATIoNorILLInoIs. a

TELEPHONE-EXCHANGE. SYSTEM.

T all whom it may concern.'

Be it known that I, LIPA POLINKOWSKY, a subject of the Russian Emperor, residing at 19 `Rue Brialmont, Brussels, Belgium, have invented certain new and vuseful Improvements in Telephonelxchange Systems, of

which the' following is a full, clear, concise,

-and exact description.

This invention relates to telephone eX- change systems, and more particularly tol systems in which a group of' Acalling or incoming lines are served by and connectible to by a group of line finder switches auto- `matically operating when a call exists upon. 'one of such lines'to search for and seize such line.

' A particular feature of the invention involves means .whereby a signal or indication 20 i a group of lines are available to hunt for 'will be given when and only when an insufficient number of line finders accessible to and seize a line upon the initiation of a call upon one of such lines.. lA furtherv feature provides simple and positively operating means whereby the number of occasions that the condition above referred to arises may be recorded for any given period ,of time, so that a positive record may be kept which will indicate whether vthe number of line finders `serving the group of lines is sufficiently large to maintain'the usual'traiiic' requirements 'of the exchange.

In vsome cases it will be sufficient if a lsingle line finder switch is always available when a call is initiated upon one of the lines to which such line finder switch has access,

In this case no indication is necessary, and no record need be made unless when the call is initiated, no line finder switch is available.

Under other circumstances it will be necessary for the trafiic requirements of the -eX- change or for other reasons, that a definite number, more than one, of line finder switches should be available to hunt ferrand seize the calling line immediately that the call is initiated thereon.

.The invention' will be first described where the requirement is that only one line finder switch need be available when the call is I initiated on the calling line. The drawings l showso much of thecalling line and the apassociated therewith, asis necessary tp illus' paratus associated therewith, and so much of aline finder switch, and -the-applaratus Specification of Letters lratent. 'Pteni-d Mjayl 18 19150v Application mea-.august 17, 1914. serial Notar/,131.

trate the invention. VThe* calling or incoming li-ne is represented by the conductors thereof, 11 and'12. V:Upon the initiation of a call upon such line, the circuit for` direct current will be closed between such conductors,

as for-eXample,-at the-substation thereon by the subscriber removing his receiverfrorn -its Switchhook, and current will pass through the line relay'lS of the line "and over the vback contacts of the armatures of the cutoff relaylt ofsuch line to energize the relay 13 inthe usual manner. -The energization of the relay 13 closes the circuit for the pilot relays 15, l6,`which circuitalso places selectable potential upon theterminal 17 of the all of such idle line finders. These line find# ers will thereupon begin to move, testing by their test brushes 22; the terminals 17 of all of the lines to which'they have access. The first one of the line finders whose` brush 22 coming into contact with the terminal 17 and finding theselectable potential thereon, will have the relay 23 thereof energized over its left-hand highv resistance winding and the sequence switch'contact 2st, the path to earth for such circuit being through the inf terrupterlbrush 25 and the winding of relay 26. .Relay 26,however,does not become ener* gized upon the closure of this circuit, its winding beingshunted 'through thel inter rupter brush 25. The line finder continues to move until its brushes, including the brush 22, are centered uponA the terminals of the calling line when, the circuit through its interrupter brush 25 being opened,fthe 'shunt around the power control relay 26 isl removed, and such relay willrespond, opening the 4circuit for the power magnetl 2-1 and closing the circuit to the holding magnet 27 of the line Ifinder switch, stopping suchY switch with its brjushes accurately in posiv`tion upon the terminals of the calling line.

As soon however`s the relay 23 was energized when the brush 22 came in Contact with -the terminal '17 upon. which existed selectable potential, it closed, through .its

armature, the arallel circuit through its low resistance r1ghthand winding in shunt of its high resistance left-hand winding. This low resistance circuit so reduces the potential upon the terminal 17 that any other line finder switch whose brush 22 comes in contact with the terminal 17 of the same line finds insuliicient potential upon such terminal to energize the relay. 23 over its lefthand high resistance winding. No other line nder switch, therefore, will be able to seize this calling line.

Uoincident with the stopping of the line iinder switch by the energization of the relay 26, such relay closes a circuit for the sequenceswitch 28 over the vsequence switch contact 29, to drive such sequence switch out otite first position to come to rest in its third position. In the second position of the sequence switch a circuit is closed over sequence switch contact 30, the line nder brush 31, and terminal 32 individual to the calling line, to energize the cuto relay 14 of such line. This relay by Venergizing opens the circuit of the line relay 13 which in turn by de-energizing, opens th'e circuits of the pilot {relays 15 and 16, which in turn will de-energize unless some other line of the same group of lines is calling, and has not as yet been seized by a line nder switch.

It will be observed that the conductors connected to the armatures of the line relay 13 of the various lines are connected to the circuit of the pilot relays 15, 16 at the common point 33. 1f upon the energization of the line relay 13 upon the initiation of a call and the consequent energization of the pilot relays 15 and 16 no line iinder switches hav ing access to this line were idle, that-is, no

vline finder switches stand with their sequence switches 28 in the normal or lirst position,

no circuit for the guard relay 18 is closed. f

The armature of the relay 18 therefore remaining inits retracted position, a circuit is closed for the guard lamp 34 which will indicate to the attendant at the station in which the group of lines referred to terminate, that a call has been initiated on one of such lines, Vand no line finder is available to extend the circuit of such line. Furthermore, immediately that a line finder of the group having access to such line becomes idle, that is, its sequence switch reaches its first or normal position, the circuit will be closed at its power magnet 21 for relay 18 to energize such relay, and the guard 1am 34: will beA extinguished. The attendant wi l thereby be informed that, unless the calling party has abandoned the call, a line finder is at that time searchin for the line on whichsuch `call exists. n association with the guard lamp 3e' there is also provided a meter 35 the magnet of which will be ener* gized whenever the guard lamp 34 is light.- ed, and will cause the meter to register, ence,

whenever such magnet is denergized coincident with the extinguishment of the guard lamp 34 either upon a line finder becoming idle to search forthe calling line, or upon the abandonment of the call by the calling subscriber. It will be obvious therefore that this meter will indicate the total-number of delayed or abandoned calls in the group for any given period, which delayed o r abandoned calls are traceable to theinsulicient number of line finders associated with the group of incoming lines to which such meter is individual. 1t will be 'further observed that if when there are no line finders available to search for lin@ upou'which calls are initiated at any given` time two or more lines should be calling in the group, the guard lamp 34: will be lighted, and the meter prel i pared for registering immediately. When a line finder becomes available to search for the calling lines, the lamp will be extinguished and the meter will register. When however the line finder has found and 'seized one'of the calling lines, the circuit for the relay 18 will be opened at its sequence switch contact 20, and if unseized calling lines still exist in the group, and no line finder has meanwhile become available to search for and seize such lines, the guard lamp will again be lighted and the register 35 again prepared for registration. It will therefore be apparent that the guard lamp 34 will provide an efficient indication of the occasions when no line finder switch is available to eX- tend the circuit of a calling line, and the register 35 will provide an accurate record of the number of such occasions.

In systems in which the traffic or other requirements make it imperative that more than one line iinder vswitch should always be available to search for and seize a line upon which a -call is initiated, in order that the eX- tension of the callinvline should be accoinplished by a line finder switch with the .least possible delay, it is only necessary that the guard relay 18 should be so adjusted that it will only respond when, upon the initiation of a call, the minimum required number of line finder switches are in idle position. That is to say, when the minimum required number of available line finder switches is two, the guard relay 18 will beso adjusted that it will onl attract its armature when it is energize over a circuit includin the power magnets 21 of two oi' such line-finder switches in parallel. The guard lamp 34 will therefore indicate and the register 35 record all occasions on which the initiation of a call upon a line of the group occurs, wh`e there are not two line finder switches at Ileast available to extend the circuit of such line. It is obvious of course that the minimum required number of line finder switches available to extend number, the guard relay 18 being adjusted to be energized only over the power mag,-

`nets 2l of respectively 3, 4,'or any other given number of line finder swltches.A

The invention herein is obviously adaptable either for systems in which the incoming calling ,lines terminate in main central oiiices, such lines being either subscribers lines, or incoming trunk lines, and in which offices there is, or may he, always present an attendant,orto satellite offices where an attendant need not be present,l the register maintaining a complete and accurate record which may be observed whenever the attendant visits the satellite otlice, and .indicates definitely whether the number of line finder switches serving the group to which the register is individual is suiiicient to fulfil the traiiic or other requirements of the exchange.

In the drawings, the apparatus and circuits individual to an incoming line, the apparatus and circuits individual to a line finder switch and the apparatus and circuits common to the group of lines and group of line finder switches are shown separated by dotted lines, so that the relation of lthe va'- rious elements of the system inwhich the invention is shown embodied may be made most clear.' p

1. In a telephone exchange system, the combination Awitha plurality of lines, a plurality of'nder switches in which said lines terminate, means for causing one of said switches to connect with a calling line uponA the initiation of a call upon such line, indieating means, and means actuated in initiating a call upon any of said lines to operate said indicating means each time there is not available a definite number of such switches vto connect with such calling line.

2. In a telephone exchange system, the' I 'combination'with a group of lines, finder switcheslfor said group, means for causing one of said switches to connect with a.eall ing line of the group of lines upon thezinitiation of acall upon such line, indicating lmeans for said group of lines, and means actuated in initiating a call upon any of said lines to operate the indicating means each time there is' not available a de'nite numberv .of switches to connect with such calling line.

3. In l a telephone exchange system, the j my name this 28th day of July A. D., N14.

I combination with a plural'ty of lines, finder switches to which such lines are multiplied, means for starting the switches in motion upon the initiation of a call in any of the lines, and indicating means individual -to said lines and operated eachtime there isnot available a deinite numberl of switches'` 60 va de to connect with a calling line.

4. In a telephone exchange system, the combination wlth a plurality of lines, a plu- 5. In a vtelephone exchange system, lthe combination with a plurality of lines, :Ender ,switches in which said lines terminate,

means for causing one of said switches to connect with a calling line upon the initiation of a call upon such line, indicatin i means and a pilot relay for said lines, sai pilot relay being energized upon the initiation oi' a 'call upon any line-'and closing'at one point the circuit of said indicating means, acontact closed when any of said switches is idle, and a relay contrplled by said contact to open at another point the circuit of said indicating means.

6. vIn a telephone exchange system, the combination with a plurality of lines, finder switches for saidlines, driving circuits.

therefor, a pilot relay adapted to close the driving circuits of any of said switches which are in normal position upon the ini-A tiation of a call, indicating means for said lines, said pilot relay also closing at one point the circuit of said indicating means, and 4a relay the conductor common to the driving circuits of the switches operated if the driving circuit of any switch is closed upon the energization'of the pilot relay to open at another point the circuit of said indicating means. 7. In a telephone exchange system, `the combination with a pluralityof lines, aplu- I rality of automatic switches adapted to serve said lines, means for causing one of said switches to be associated with a calling line, indicating means adapted 'to be actuated upon the initiation of a call upon any of said lines, and a relay adapted to prevent the actuation of said indicating means if any of'said switches is idle.

In witness whereof, Iv hereunto subscribe t LIPA POLINKOWSKY. Witnesses i i F. T. IWOODWARD, .H. Tuoi: SHERMA. 

